Burning the World in Unholy Fire
by CP Nightshade-Eyes of Asteria
Summary: "You have a dark heart in you, Valentine's daughter." Those were the words Sebastian had told her what seemed like an eternity ago. Now, in Edom, she feels the very truth of those words in her very soul. When darkness takes the daughter of Angels, what light is left to shine upon the world? Dark Clary/Sebastian. CoHF spoilers.


**Okay, I know I have another fanfic kinda just sitting there right now. But I just read the City of Heavenly Fire, and this idea crossed my mind fairly early in the book. So when it gave me the opportunity to actually happen at a reasonable time, well it happened. There are spoilers in her the CoHF, as well as incest. Personally, I'm no huge fan of it but this idea grew inside my head and now here it is. Oh, and this is my first MI fanfic, so tell me how I do.**

She saw Jace swallow. He dropped the bracelet into Sebastian's open palm. "Clary is yours," he said, and stepped back.

Sebastian snapped his fingers. "You heard her," he said. "All of you. Kneel to your queen."

Clary found herself wanting to protest, to cry out, to tell them not to kneel. She forced herself into stillness, silence. She watched as the Endarkened began to kneel, one by one, their heads bowed; the last to kneel was Amatis, and she did not bow her head. Luke was staring at his sister, his face flayed open. It was the first time he had seen her like this, Clary realized, though he had been told of it.

Amatis turned and looked over her shoulder at the Shadowhunters. Her gaze caught on her brother's for just a moment; her lip curled. It was a vicious look. "Do it," she said. "Kneel, or I will kill you."

Magnus knelt first. Clary would've never guessed that. Magnus was so proud, but then it was a pride that transcended the emptiness of gestures. Despite her earlier resolve to not want her friends to kneel down, she kept hearing Sebastian's voice in her head, repeating the same saying over and over. _You have a dark heart in you, daughter of Valentine._ She felt her will, which she hoped had foundations deep enough to withstand anything Sebastian has planned begin to shake a falter. She felt the darkness, felt it seep out from within her very core and she felt its icy cold tendrils grip her heart like a vice.

She expected it to be unpleasant, to be painful or heart wrenching, but Clary did not expect the darkness to feel so… alluring. She was surprised, but in the good way. She felt it seep into her soul; the very thing she had hoped to never feel. Though now that she had felt it, if only for a brief time…

She wanted _more_.

And she got her wish as Alec soon followed Magnus, kneeling before Clary on her throne of melted gold and ivory bone. Isabelle followed soon after, then Simon, then Luke, drawing Clary's mother beside him. And lastly Jace, his blond head, now dulled in Clary's sight. His brightness, the light that was increased tenfold by the heavenly fire the used to rage within him, and now that Clary had siphoned the fire into Heosphorus by the work of Ithuriel's rune, he seemed to be even more ashen. She had originally planned to use the holy fire on Sebastian, but now she was starting to like the idea of ruling from her pale throne, her brother at her side.

Once they were all bowed before her, Sebastian moved towards the platform taking the steps two at a time towards Clary, and reached up to take her hands; she let him draw her, until she stood in front of him. He was still holding her. His hands felt like bracelets of fire around her wrists, spreading a tingling sensation throughout her body. "You accept it," he said. "You accept your choice?"

"I accept it, she said, looking at him with absolute directness. "I wholeheartedly accept." By now, a small smile had crept to her face of its own accord. She could feel the shadows inside her reveling in joy, and the cool pleasure that it shared with her only made her grin wider.

Sebastian's onyx eyes locked with hers. "Then kiss me," he said. "Kiss me like you love me."

Her original thought when Jace and her had created this plan and brought this very action up was that she would be disgusted. She believed she would recoil, be disgusted by the fact that she might have to kiss her brother. Now, she didn't see Sebastian as just her brother. She saw him as a king, as a conqueror. She could see him leading battles and slaughtering his enemies and bathing in their blood. The darkness in her wanted to join, and she could not resist the pull it had on her. So she leaned in, rising up to the tips of her toes, and kissed Sebastian.

When their lips met, she could almost hear the shadows in her soul cry out in joy. The chill it brought to her body made her shiver in pleasure. She wrapped her arms around his neck and deepened the kiss. Clary opened her mouth and swirled her tongue across Sebastian's lips, to which he eagerly opened his mouth and their tongues met. Clary would've of continued, but she heard Jace yell out her name, "Clary!"

She drew back from Sebastian with a look of annoyance on her face. She looked into her brother's eyes and smiled slightly, before giving a teasing wink and whispering to him softly, "Later." His face broke into an enormous grin. She unwrapped her hands from around his neck before she turned and looked down at Jace who was now standing. She gave him a scathing look before addressing him evenly, "Jonathon Herondale."

Jace recoiled at her tone of voice. Her normally soft yet firm voice was replaced by an emotionless, cold one, eerily similar to tone Sabastian used. He looked at her, noticing how the bright and lively demeanor she once had was replaced by a shadow, emotionless and icy. "The plan," he said. "What are you doing?" His face was so shattered, so weak. Clary felt the darkness stir, obviously aware at the person trying to remind her of the plan to kill Sebastian, her king.

Clary cocked her head to one side, staring at him as if she was dissecting him to find out what was wrong her. "I suppose those who do not share the Morgenstern blood cannot feel it," she began. "You feel the angel's blood thrumming in your veins, leading you to do good in the world."

Clary began to descend from the dais, and she stood inside the circle of dark runes. The windows still stood, and Clary looked at the shimmering green beauty of Idris and Alicante with disgust. The shadows that swirled in her soul didn't like the look of such untainted lands, and it recoiled even at the sight of them making Clary feel slightly clammy just staring at them. She diverted her attention back to Jace. "You have the blood of Raziel, a heavenly angel through and through," she said, and then turned and looked at Sebastian. "My brother and I, we have the blood of Lucifer, the morning star. We were both destined to fall, sooner or later."

Jace looked at her, confused as to why Clary was acting this way. Concern showed in his eyes, and with a further look it showed in the eyes of those around him. She thought, and hid a snigger, that if her "friends" thought she needed help, that they didn't know her well enough to call her "friend" at all. Clary stared into Jace's golden eyes, her emerald ones darker than he'd ever seen. "You can't believe that," Jace said. "You can't, it's just not you."

Clary snorted in a very un-lady like fashion. "And who are you to dictate what I can believe?"

Jace as at a loss for words, but his confrontation spurred Simon into stepping forwards. "You can't Clary. You were the greatest of all Nephalem, your powers and your increased angel blood made you the brightest of all stars."

At this, Clary just gave an agitated sigh. "You need to seriously work on your listening skills," she said as she put the heel of her hand against her forehead. "Lucifer was the brightest of all the angels in heaven, and he fell. So as I said earlier, it goes to point that those with the blood of the morning star fall from heaven's grace."

This time, it was Jocelyn who spoke up. "And you're okay with that!" she yelled at Clary. Jocelyn started to move forwards, but Amatis and the other Endarkened had risen and moved to protect their queen. They moved to restrain Jocelyn, but Clary simply raised her hand and they formed a loose semicircle before her.

Clary gave her mother a cool, collected looked. "Dear mother," she said with a voice of venom. "How does it feel to sire the King and Queen of Edom? I doubt the Shadowhunters would welcome you with open arms, but then again neither would we." Jocelyn recoiled away from her daughter. "You are the birthmother to two of the most powerful beings that can or will wield demonic power, which leaves the question: what does that make you?" Clary gave her mother a cruel smirk, and she felt the darkness thrum with glee.

Jocelyn began to cry, and Luke came up to her and hugged her tightly. Jocelyn spoke, tears and sobs choking her speech, "You are no longer any daughter of mine."

At this Clary just raised an eyebrow and her lips quirked even more. "How fitting," she replied, her voice cutting like a blade. "Because you are no longer any mother of mine." At her reply, Jocelyn cried harder into Luke's shoulder. Clary cast a look around at the company before her, noticing them all glaring at her with hatred except for Jace, who merely glared at Sebastian upon his throne instead.

Clary moved up so she was right behind Amatis. "See that our guests are moved through the window," she told the King's, and now her, lieutenant. "I wish to spend time with my King and have no time to spare for such a rebellious and ignorant bunch."

Amatis and the other Endarkened moved forwards to usher the werewolf, Nephalem, Daylighter, and warlock towards the window that lead to Idris. Clary turned around to ascend back to her throne next to Sebastian, but turned around when the sounds of combat came from below. Jace had gotten past the Endarkened somehow and was making his way towards Clary. Clary looked at his gaze, and saw his eyes were locked on blade at her hilt. Knowing what he planned to do, she snarled and drew Heosphorus from its scabbard.

The blade was at the throat of Jace in a second, golden flames licking along the stars of the Morgenstern blade. She narrowed his eyes at the Herondale boy as the Endarkened surrounded the both of them. They hissed at Jace, and pulled him back savagely so that he was on his knees before her. "Now what," she began, "did you hope to gain from doing that?"

Jace just continued to look at her with betrayal in his eyes. Finally, after he saw the Clary's attitude was unchanged he answered. "The plan," he said. "I was going to finish the plan and take Heosphorus and stab it through his chest." He pointed at Sebastian who was now standing at the edge of the platform, fists balled as he glowered at Jace.

Clary moved forwards as to deliver a blow, but she just crouched in front of the Herondale. "If you so much as make another move for the blade or against Sebastian, I will kill you." She gave him a once over. "And I'll enjoy every long second of it." She addressed the Endarkened, "Get him out of here. Now!"

The Endarkened ones moved to finally take him out with the others. Just before the last one was thrown back into Idris, Clary heard Jace ask, "Why?"

Clary gave a low chuckle, and despite Jace not being able to hear she answered him. "Oh Jonathan, you should've realized by now. The brightest of lights always cast the darkest of shadows." She turned away from the window and gave Sebastian a smile as he descended to finish off the circle to close off this world from the other. When he bent down over the rune circle, he traced one last rune into the ground.

At first, the windows seemed to crack and fracture. Spider webs chased each other to and fro along the image of Idris and other worlds. After that, they fell like a waterfall: slow at first, tinkling ever so slightly as the hit the ground before roaring and hitting the ground in a cascade of melodically ringing pieces.

Clary moved over to Sebastian so that when he straightened up and turned around she would be right there. When he did straighten, Clary put her arms around his neck once again and rose to her tip toes and kissed him quickly. Sebastian leaned into at first, but then pulled back for a second. He turned his head to the remaining Endarkened and spoke, his voice carrying its normal high authority, "Leave us."

When the Endarkened had left, Sebastian turned back to Clary and slammed his lips ferociously into hers, eliciting a small gasp from the red head. Sebastian's tongue met Clary's and the wrestled for dominance. Clary felt herself wrap her legs around his waist and his hands move down towards her hips. She felt the darkness in her trill again, sending another shiver of pleasure through her body. She drew back a little and gasped when Sebastian started to massage her rear with his strong hands. Her brother moved to kiss her neck, sending ecstasy coursing through her cells.

Clary was about to suggest they take this somewhere more suitable, but she didn't get the chance as a rich, velvety laugh echoed off the walls. The pair pulled apart and looked down at the base of the dais to see a tall woman with hair the color of ebony and eyes like molten obsidian. The woman's skin was pale under the deep black dress she wore. The dress itself went down to her ankles and draped itself over the woman's shoulder. Clary could only compare the woman to a celebrity or super model, and even then it barely held a candle to the woman's beauty.

Clary was confused for a small moment, before she recognized the woman. "Mother!" Sebastian said, voice sounding happy and carefree which was incredibly new to Clary. Sebastian took a step back from Clary, giving them acceptable distance though he still held Clary's hand in his own.

"My dear son," Lilith said to Sebastian, approaching him with arms wide open. Sebastian let go of Clary's hand and embraced Lilith. Lilith moved back and put her hands on his shoulders in a surprisingly motherly gesture. "Are you alright? Did everything go to plan?"

Clary found the concern in Lilith's voice odd, considering that all she knew about her was that she was the mother to almost every demon, though Sebastian was unperturbed. "Everything went fine, but not exactly according to plan," he told Lilith, a grin breaking across his face. "It went better than any of us could have foreseen."

Lilith gave him a questioning glance, raising one of her dark eyebrows. "Oh?" she began, a smile forming across her perfect features. "Please do share; I love it when everything works out."

At this, Sebastian stepped back from his mother and grasped Clary's hand again. "It would seem, after an interesting turn of events, that I did not need to persuade Clarissa after all," Sebastian looked at her and his eyes held such pride, that Clary felt overwhelmingly giddy. "She came of her own free will, and even disowned Jocelyn right here. Even with all the amazing things I have seen, Clarissa managed to strike me with awe once again." Sebastian bent over and gave her a quick peck on the lips, making heat rise up and flush her cheeks a light red.

Clary, feeling the need to supply some sort of input, spoke up, her voice sounding surprisingly calm, "It was nothing special, just the bald truth." At this Sebastian just gave a booming laugh.

"Just the bald truth?" he asked, his voice carrying a playful edge that once again surprised Clary. "What was it you said? About following in Lucifer's footsteps?"

Clary looked at her feet, feebly attempting to hide the heat rising to her cheeks. "I said that the Morgensterns have the blood of Lucifer in our veins, so it is only fitting that we fall as he did." Clary looked up again, seeing Sebastian's onyx eyes so lively. It was strange, but she could still see the coldness that was waiting, lurking just beneath the surface. It was that coldness that the darkness in her desired, but she could not deny that she enjoyed this side of Sebastian as well.

Clary felt a pair of delicate hands grasp her shoulders and she looked to see Lilith looking at her with what seemed to be actual respect. "Oh my," she said, her voice sounding as soft as silk. "I do believe you were right Sebastian. Clarissa here will make an excellent queen."

Lilith than took a step back, looking over the both of them as a pair. She grinned, and then beckoned them to follow. "Come now," she began as she turned to walk out of the Garde. "We have much to do for our new queen."

Clarissa and Sebastian followed behind Lilith, hands intertwined. As they exited, Sebastian leaned over and whispered into Clary's ear, "Later?"

Clary couldn't help to wolfish grin that spread across her face. She leaned over towards his ear and whispered back, "Later." And the darkness in her soul chorused in agreement.

**Thank you all who read this, and please leave a review or send in a PM. Criticism is welcome, but flames aren't.**

**CP out**


End file.
